hopkinson



(No Model.) I 6 Sheets-Sheet 1.

J. HOPKINSON.

APPARATUS FOR MEASURING AND RECORDING ELECTRIC OURRENTS. No. 277,731. l jmtented May 15,1883.

Phuloiilhogmphlr, Wuhinglun. I16- (No Model.) GSheets-Sheet 2.

J. HOPKINSON.

APPARATUS FOR MEASURING AND REOORDILLQ ELECTRIC GURRENTS. No. 277,731. f'lahel atented May 15,1883.

u, PETERS. mo-lithogmphlr whammy c.

(No Model.)

7 6 Sheets-Sheet 3.

J HOPKINSON.

APPARATUS FOR MEASURING AND RECORDING ELEGTRIG UURRENTS.

No. 277,731. 7 Patented 13w 15,1883.

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(No Model.) 6. Sheets-Sheet 4. J. HOPKINSON. APPARATUS FOR MEASURING AND REGORDING ELECTRIC OURRENTS.

Patented May 15, 1883.

(No Model.) 6 SheetsSheet 5.

J. HOPKINSON.

APPARATUS FOR MEASURING AND RECORDING ELEOTRIG CURRENTS.

No. 277,731. Patented May 15,1883.

(No Model.) Q 6 Sheets-Sheet 6.. J. HOPKINSON.

APPARATUS FOR MEASURING AND RECORDINGELEGTRIG GURRENTS. No. 277,731. Patented May 15,1883.

UNITED STATES PATENT OFFICE.

JOHN-HOPKINSON, OF WESTMINSTER CHAMBERS, COUNTY OF MIDDLESEX, ENGLAND.

APPARATUS FOR MEASURING AND RECORDING ELECTRIC CURRENTS.

SPECIFICATION forming part of Letters Patent No. 277,731, dated May15, 1883.

Application filed July 31, 1882. (No model.) Patented in England January 4, 1882, No. 49.

.To all whom it may concern:

Be it known that I, JOHN HoPKINsoN, a subject of the Queen of Great Britain, andresiding at Westminster Chambers, county of Mid- 5 dlesex, England, have invented certain Improvements in Apparatus for Measuring and Recording Quantity of Electricity, and in the v means or apparatus employed therefor, (for which I have obtained a patent in Great Brit- Io'ain, No. 49, dated January 4, 1882,) of which the following is a specification.

My improvements relate to means for measuring the whole quantity of electricity which passes through a conductor. For this pur- I 5 pose I make use of a centrifugal governor or centrifugal apparatus, and control its velocity by electrical or electromagnetic apparatus. Thecentrifugal force of the governor may be opposed by the attraction or repulsion 7 20 of one conductor conveying electricity on another conductor conveying electricity, of an electro-magnet for its armature, or of a solenoid forits core; or the centrifugal force may move one contact-piece or its equivalent and 2 5 the electrical apparatus a second contact-piece in such wise that as the speed of the gov-.

ernor increases the former piece or its equivalent is moved from the second, while as the electrical force increases the second piece fol- 0 lows up the first. When the centrifugal'force is mechanically opposed to the electrical force,

the governor may act by bringing a frictionbrake into action; or it may act by making and breaking an electrical contact. The gov- 5 ernor may be driven by a small electricmotor; or in thecase of usinga brake the governor may be driven by clock-work. In order to prevent the force due to the electro-magnet or its equivalent from putting undue pressure on '0 the bearings of the centrifugal governor, I find it advantageous to arrange the-electro-v magnet symmetrically about the axis of the governor. When the governor and electromagnet or its equivalent carry electrical con- 45 tact-pieces, the ordinary mechanism of the governor may be replaced by a heavy fluidrent. The number of revolutions of the governor may be counted and recorded by clockwork or other suitable mechanism.

'In the accompanying drawings, Figure 1, Sheet 1, is a side view of my electric meter, partly in section,'on the line Q R, Fig. 3. Fig. 2, Sheet 2, is aface view; Fig. 3, Sheet 3, a rear view, partly in section; and Fig. 4, Sheet 4, a sectionalplan on the line S T, Fig. 1; Figs. 5 and 6, Sheet 5, views ofmodifications; andFig. 7, Sheet 6, and Fig. 8, Sheet 4, views of another modification.

Referring to the meter shown in Figs. 1, 2, 3, and 4, N is the frame of the apparatus, which preferably carries a number of registering-dials, s, operated by suitable multiplyinggear, 1", to which motion is communicated from the operative parts of the meter, as more fully described hereinafter.

At the lower'part of the frame is arranged an electric motor, M, the coils of whose electro-magnets a a are in a shunt-circuit from the main circuit the current in which is to be measured, the shunt-circuitbeing represented by the double-headed arrows. This motor M is arranged so that the axis of its rotating armature I), mounted in suitable hearings, will be vertical, and the upper end of this axis is coupled to or forms part of a shaft, 1. To this shaft 1 is secured the half-core m of the electro- Inagnet 0, whose coils j j in the main circuit (indicated by the sin gle-headed arrows) are car ried by a stationary tube,7.:, secured to the frame, A second half-core, i, is also carried by the shaft I, so as to rotate therewith, but being free 'to slide thereon longitudinally to an extent ring it is connected by an insulated conductor,

g, with an insulated ring,]', on the lower end of the shaft Z. On this ring bears a brush, 6, secured to one of the insulated posts 0 (1, carrying the commutator-brushes c d, which bear on the commutator I) of the armature of the To balance the movable core t of the electromagnet O, and govern its action, the said core is suspended by links 0 from the short arms of bent lovers 0, pivoted to arms on the rotating shaft 1 and carrying governor-balls n. Springs t are also preferably employed to balance the core 43. The upper end of the shaft 6 is provided with a worm, (1, gearing into a wormwheel on a shaft, 7", which thus transmits the motion of the shaft l to the registering; devices 0' 8, above referred to.

The shunt-circuit for operating the motor enters, as indicated by the double-headed arrows, at the insulated post 1, thence to the fine-wire coils of the electro-magnets a, conductor 9 1 brush 0, armature 1), brush d, brush 0, ring f, conductor g, ring It, points h i, and thence to IlllGfI'ftlllGftlldOtlliitbPOSllel. The main cireuit(indicated by singleheaded arrows) enters at insulated post 3, passes through the coarse-wire coils j of the electro-magnet O, thence to the frame atj, Fig. 3, and out at 4 The weights n of the governor and the tension of the spring t are so adjusted that when there is no current passing through the coils the core 7: will be in a raised position, with the points it and i out of contact, and there will be nocireuit through the coils oftheelectric motor, and the armature b will consequently remain stationary; but when the current begins toflow through the coil it causes attraction between the fixed tube is and the flange of the core 1 which extends to the periphery of said tube, and also between the two cores m and i, so that the latter is drawn downward, and the points it and i" brought together to close the shunt circuit through. the coils of the motor, and cause the armature of the latter 'to revolve, and with. it the shaft 1 and cores in and 'i, with the governor devices. -As these revolve, the centrifugal force on the governor-balls tends to lift the core 11 in opposition to the magnetic attraction, and this centrifugal force is proportional to the square of the speed of revolution, while the magnetic force is proportional, within certain limits, to the square of the current in the coil. This proportionality is not absolutely accurate; but I so long as the rim of the core and cylinder are not nearly saturated it is found to be sufficiently nearly so for practical purposes. These forces should exactly counterbalance each other, for if at any instant the speed be too great the core i will be raised and the circuit through the coils of the motor broken, and the speed will be reduced, owing to friction of the bearings and other parts of the mechanism,

while if the speed be too low the contact at h" 'i will be made, and a current will pass through the motor, which will increase the speed ofthe system until the centrifugal force overbalances the electromagnetic attraction, and again breaks the contact at h i, The result is that the shaft 6 will revolve with an average velocit y proportional to the current passing through the coilj in the main circuit. By arranging the shaft 1 centrally within the solenoid there will be no undue pressure on the bearings arisin g from electromagnetic effects on said shaft.

The core t may be connected to the shaft 1 through the medium of groove and feather; but for ordinary purposes the connection of the levers 0 and links 0 will keep the core from turning independently of the shaft.

The operation of the meter is not dependent for its accuracy upon the power of the motor, for if the motor be more powerful the contact at h i will have a shorter duration; but the average speed of revolution will remain the same for a given current in the solenoid. The capacity of the meter, or the greatest current it will register, is, however, limited by the maximum speed of the motor, as well as by the limit of magnetization of the cores of the solenoid, for when the maximum is surpassed the speed can never become suflicient to cause the governor-balls to fly out. The theory may be stated algebraically thus: Let G be the current in the solenoid; F, the attractive force of the fixed part of the core and of the iron cylinder on the movable part of the core which is sus- -pended from the governor; let a be the numberof revolutions per minute made by the governor, and G the tension ofthe links 0 in excess of the tension in them when theinstrument is at rest. Then, if the rim be not near saturation, FzaC nearly when ais constant; also, Grim when I) is constant. Now, if G F, the core i will be raised a little, its further rise being stopped by a collar on the shaft, and the contact will be broken at h t. It G F, the core will be pulled down and contact made at Mt,- hence, if aG bn there will be no contact at h i, and the machine will be retarded. lt aG Zm there will he contact at h i, and the machine will be accelerated. The result is that (L0 is always very nearly equal to M being alternately a little greater and a little less; hence, taking the average value of a", we have with practical accuracy aU' L-Infi, and therefore a proportional to O.

In the modification shown in Fig. 5 the solenoid, shaft l, and cores are similar to these de scribed, and the governor devices for the core i, although slightly differentfrom those shown in the preceding figures, will be readily understood without description. In this case, how ever, instead of driving the shaft 1 by an electric motor, and controlling the speed by making and breaking the sh nut-circuit through the motor, the shaft is driven by suitable clockwork, and the speed is regulated by the flange of the core i coming into contact with frictionscrewsu u, carried by a fixed part of the frame.

Therefore, when there is a decrease of current in the solenoid, and a consequent elevation of the core 17, the flange of the latter will rise into contact with the said screws, which will act as .frictionbrakes to proportionately decrease the speed of the shaft Z. The theory of operation is very similar to that of the instrument above described. A very small upward pressure against the brakescrews causes much friction and maintains a close approximation to proportionality of centrifugal forcean-d magnetic attraction.

In the modification-shown in Fig. 6 the-shaft Z is intended to be driven by an electricmotor in the shunt-circuit, as in the device shown in Figs, 1, 2, 3, and 4, and thc'speed regulated by the making and breaking, atom, of the shuntcircuit, which, as before, is indicated by the double-headed arrows. Thecoret' isin this case fixed to the shaft, but insulated therefrom, and in the enlarged flange of the core are formed radial slots for the reception of small blocks e, which are carried by flat pendent springs to, suspended from the cross-head a. The inner sides of the weights or'blocks 12 make contact with the adjustable screws x; but the blocks are insulated on their outer sides, so as not to make electrical contact with the adjustable stops .2 z,.which are simply to prevent the pieces 1; from flying out too far under the centrifugal force. They are attracted inward by the magnetism of the core t'. The core t is connected with the shunt-circuit by a brush-contact similar to that shown at e, in Fig. 1.

The theory of the operation is similar to the first case. If the attraction of thecore t for the armat'ures c is greater than the centrifugal force, contact will occur between or and v, a current will pass through the motor which drives the system, and there will be an increased speed until the centrifugal force is greater than the magnetic attraction, when the pieces 1; n will fly out and break the contact at w,

' and there will be thereupon a retardation'until the velocity falls to a point at which the attraction is greater than the centrifugal force. Instead of constructing the apparatus so as to counterbalance the centrifugal force against the electromagnetic force, as above described, the centrifugal devices may be provided with one contact-piece and the electrical apparatus with another contact-piece, so that as the speed of the centrifugal governor increases, the contact-piece on the governor is moved away from the other, while as the electrical force increases, the contact on the electrical device follows up the contact on the governor. The modification shown in Figs. 7 and 8 illustrates a method of carrying this into effeet. In these figures, A is a shaft driven like the shaft 1, above described, by an electric motor, and carrying three vertical tubes, B, B, and (J, communicating witheach other, one tube, 0, being in line with the axis, and the others,B,being at a distance radially from the center of the shaft. These communicating tubes contain mercury, so that when the shaft with the tubes,is revolved,themercury,owing to the centrifugal force, will rise in the outer tubes, B, and fall correspondingly in the central tube. Within the central tube dips a pendent coutact-finger, D, carried by an arm, D, secured to a pivoted coil, F. This coil F is mounted on knife-edge bearingswithin a turn is connected to one of the terminals of the coil F, while the other 'terminalof the latter is connected to the flexible strip H and exit binding-post L. The coil F is balanced on its bearings by the weight of the arm D and piece D at one end and by a tension-spring, F, at the other. The axis A is in the shuntcircuit which is indicated by double-headed arrows in Fig. 7, and which contains the coils of the electric motor, and it is through the contact of the finger D with the mercury that this shunt-circuit is maintained. The passage of the main current through the coils E and F causes/the latter coil to turn on its bearings, so as to depress the contact-piece D. The centrifugal force, on the other hand, lowers the surface of the mercury in the tube 0. The theoryis as follows: Let to be the angular velocity of rotation in circular angular measure andvseconds; r, the radius from the axis of rotation to the center of one of the outer tubes. Then, neglecting the diameters of the tubes in comparison with r, the difference of .2 2

. y when g is gravity. Now, if G be the current in the coils E E,the coil F turns from its neutral position through an angle proportional to G hence the contact-pin D will move through an angle equal to a0 when a is constant; hence the speed of the motor and governor .2 2 will become such that (00 being allevel of the mercury in the tubes will be ternately alittle too great or a little too small; hence to varies as O, and the whole quantity of electricity passed is proportional to the number of revolutions made. The revolutions of the shaft A may be transmitted to any suitable registering devices.

I claim as my iuvention- 1. In an electric meter, the combination of a rotating shaft, a centrifugal governor driven thereby, and measuring and recording devices actuated by the said shaft, with an electromagnetic coil in the main circuit and controlling the speed of the governor, substantially as described.

2. In an electric meter, the combination of an electric motor in a shunt from the circuit to be measured, and a centrifugal govern or driven by said motor, with measuring and recording devices and an electromagnetic coil in the main circuit, and devices, substantially as described, whereby the strength of the electric current controls the speedof the motor.

3. In an electric meter, the combination of an electric motorin a shunt-circuit, a centrifugal governor driven by said motor, and contact-points in said circuit, with measuring and registering devices and an electromagnetic coil in the main circuit, and devices, substantially as described, whereby variations in the strength of the current and speed of the governor cause the making and breaking of the shunt-circuit.

i. In an electric meter, the combination of a rotating shaft, a centrifugal governor driven thereby, and mcasurin g and recording devices actuated by the said shaft, with an electromagnetic coil and its core, through the center of which the said shaft passes, the said coil being in the main circuit and controlling the governor, substantially as set forth.

. 5. In an electric meter, the combination of a Witnesses:

(Jr-ms. MILLs, J. H. J OHNS, Both of 47 Lincolns lnn Fields, London. 

